ASTORIA, Ore. (AP) – In the Disney movie "Lady and the Tramp," a beaver at the city zoo measures out logs with his tail, cuts only once, and precisely calculates how much water is escaping through a gap in his dam.

So much for that. Now, the real world:

"They're very industrious and build wonderful things, but it's easy to see they're rodents," said Wayne Hoffman, MidCoast Watersheds Council coordinator, in a presentation, "Beavers: Engineering Healthy Watersheds" at the Seaside Public Library Wednesday night.

Some beavers are just not master architect material, and he's witnessed beaver activity that's made him shake his head.

"I haven't had a lot of success in understanding the minds of beavers," he said.

These large rodents can be big pests, making water flow where it shouldn't (onto roads, across property) and gnawing on valuable trees, but they can also be incredibly useful, Hoffman said.

The Necanicum Watershed Council, with the North Coast Land Conservancy, a land trust that owns properties from the Columbia River Estuary to Lincoln City, hosted Hoffman as a part of the "Listening to the Land" series.

Humans and beavers can coexist, maintain Hoffman and the NCLC. It just sometimes takes creative solutions.

If a culvert is consistently getting clogged because of beaver activities, a bigger culvert or a bridge can be installed. There are ways to fund these projects if a landowner can't personally afford to do it, said Hoffman and Celeste Coulter, stewardship director for NCLC.

The NCLC, as a nonprofit, has access to all sorts of grants, Coulter said.

"We're always willing to work with landowners," she said.

Landowners like Clatsop County resident Marie Smith. She has beavers somewhere on her 20 acres of property in Clatsop County. She's seen the evidence: gnawed-on trees.

She's not sure if some excess water on her property is the result of beaver activity or not, but she said she is talking with the NCLC to figure out how to work with what she has.

"Beavers can be pests," Hoffman admitted, but having them around can provide both an ecological and a public benefit.

"In my opinion, it's worth the investment," he said.

Beavers encourage other plant and animal life in and around the ponds they make when they dam streams; they can change the hydrology of stream systems across land in positive ways; and, more importantly for this region, they create excellent salmon habitat good news for conservationists and fishers alike, Hoffman said.

The dams create calm pond areas where juvenile salmon can feed and grow large and strong. These fish have a better chance of later surviving in the ocean.

But beaver populations have been on the decline.

There had been anecdotal information coming in for years: landowners who said, "Well, we used to have beavers, but we haven't seen them for a while." There were old dams that hadn't been tended in a long time and evidence of places where ponds used to be.

In 2006 and 2007, a series of studies Hoffman took part in, showed a decline in dams across the region.

Between 1992 and 1997, the Oregon Department of Fish and Wildlife's Aquatic Habitat Inventory recorded 71 dams in one area. However, in 2007, "We walked the same dams and found three," Hoffman said.

The story was similar almost everywhere they went, at the Tillamook Basin, at the Upper Five Rivers and at the Yaquina Basin.

A landscape without as many beavers, Hoffman said, is a landscape that's not as good for fish and other ecosystems. When beavers build dams, they help distribute nutrients up and down water systems. Take away the dam, and nutrients tend to collect farther away from the headwaters, leaving the headwaters thin on nutrients while other places are glutted.

So what happened?

Hoffman isn't sure. It could be a number of things: disease, predators (cougars think they're tasty), the natural fluctuations that often occur in rodent populations, legal and illegal trapping and shooting, reduced food supplies, reduced building materials, not enough beavers reaching older ages and thus living long enough to build big, strong dams that can weather winter storms.

Reed canary grass has especially played a role in this area, Hoffman said. The fast-growing invasive can quickly take over an area, squashing out other plant populations and leaving beavers with little or no food source.

What's the solution? Hoffman isn't sure. He has some ideas, though: reduce trapping, make habitats safer for beavers, restore food supplies, get rid of Reed canary grass, and reduce the beaver-human conflicts by replacing small culverts with bigger ones. Maybe even provide compensation for landowners who are willing to let beavers stay on the land.